Explosively formed penetrators or explosively formed projectiles (EFPs) may be a deadly threat on a battlefield. EFPs may be able to penetrate the armor of an armored vehicle. The penetration of the armor may cause behind armor effects, such as spall. Spall is the armor fragments that break away from the armor of a vehicle as an EFP penetrates it. These armor fragments may be extremely hot and may be accelerated to extremely high velocities. Therefore, these fragments may hit and damage equipment and injure or kill personnel within a vehicle.
An EFP may be capable of penetrating a thickness of armor that is equal to the diameter of the EFP's charge. An EFP may penetrate by exhibiting fluid-like behavior that causes the EFP to take the shape of a penetrator. This formation is due to the explosive force and the shock wave acting on a metal liner that is part of the EFP. Because an EFP is capable of penetrating thick armor from a distance, equipping a vehicle with enough armor to protect against the threat of an EFP may cause the vehicle to be overweight, and thus be less effective on the battlefield.